Muslims around the world began the month of Ramadan last Thursday, abstaining from food and drink during daylight hours.
The Islamic lunar calendar means that the start date of Ramadan moves forward by under two weeks every year versus the Gregorian calendar. In countries near or on the equator, such as Saudi Arabia, Singapore and Indonesia, this movement makes little difference to the hours of daylight critical to observe the fast.
But for those observing in the world's most northern countries near the Arctic Circle, the issue is more pressing in summer months.
In Iceland, the sun sets at midnight and returns two hours later during peak summer.
Icelandic Muslims can expect to fast for up to 21 hours and 51 minutes this year, with the sun setting at 11:57 p.m. on the final night of Ramadan on June 14.
Muslims living in countries where the sun doesn't set — or where the sun only drops momentarily — can follow one of three solutions offered by some Islamic scholars and organizations.
They can break their fast using the time of either the sunset in the nearest country that does not have near continuous daylight, the nearest Muslim-majority country, or observe Saudi Arabia's time. Otherwise, they can stick to observing local times.
Karim Askari, executive director of the Islamic Foundation of Iceland, is in no doubt which edict he will be following this Ramadan.
"I'll be going by the local time in Reykjavik," Askari told CNBC. "Going 21 hours without eating is a long time. But God willing, the majority of Muslims here in Reykjavik are doing it too."
Two mosques in Iceland's capital city have agreed to follow local dawn and dusk times to decide when they should break their fast. Other mosques and organizations have chosen to follow the times of other European countries. Askari said that one mosque in Reykjavik is following the times of a city in France.
"They can choose what they want. We have space in our community relations here," Askari said. "Some people cannot accept that they'll be eating when the sun is up, even if it's near midnight, because they are used to waiting in their home country — so they will go by local time. Others can accept that they'll have to eat even when the sun is partially up."
What may seem like extreme conditions to some is a blessing in disguise for Askari.
He is adamant that fasting in the cold is easier than doing so in Asia and the Middle East, where temperatures can soar during the day.
"It's more difficult to fast in the heat. People can end up feeling angry without eating or drinking, whereas in the cool, it's easier to go through the day."
Whichever ruling they choose, Reykjavik's 2,500-strong Icelandic Muslim population is free to choose a ruling that suits.
Slightly further down in latitude, a Norwegian Muslim living towards the north of the country can expect to fast for up to 20 hours and 20 minutes this year, while those in Oslo will observe between 18 and 19 hours of fasting.
In Oslo, actress Iman Meskini feels that the biggest challenge isn't the long hours, but to incorporate her Ramadan in a society that demands constant high productivity and may not value the need to slow down the pace of life.
"The challenge with conducting Ramadan in Norway is to fast in a non-Islamic society," Meskini told CNBC. "Everyday-life continues as usual and society expects you to perform — school, job, exams etc. — at the same level as rest of the year."
Statistics Norway estimates that 200,000 Muslims currently live in the country — a diverse group consisting of native Norwegians alongside migrants from Pakistan, Iraq, Morocco and Turkey.
While they will all break their fast in the same traditional way, with a handful of dates and a glass of water, there is no monolithic standard for Muslims in the most extreme corners of the world. For observers, that is the beauty in Islam.
"There is flexibility for Muslims," said Askari. "Each person does what they want. We can only offer what we feel in our hearts. Muslims have this flexibility inside them wherever they are."